Bring a large pot of water to boil. Cook the pasta for 5 minutes – it should still be a little firm. Drain, toss with a drizzle of oil, and set aside.

Bring a large pot of water to a boil, add the cauliflower, and cook for 5 minutes until tender-crisp. Meanwhile saute the minced garlic with a tablespoon of butter. Using a slotted spoon, transfer the cooked cauliflower to a blender with 2 cups broth, milk, oil, salt, and sauteed garlic. Puree until very smooth. You might need to do this in batches.

Preheat the oven to 400 degrees. Heat the 3 tablespoons butter in a very large skillet. Add the mushrooms and saute until golden brown.

Toss the cooked pasta, cauliflower sauce, and mushrooms together. Add the remaining cup of broth to help the consistency stay saucy.

Transfer to a deep 9x13 baking dish. Sprinkle with cheese and bake uncovered at 400 for 10-15 minutes. Some of the moisture from the mushrooms will seep out – give it a quick stir to reincorporate it and make it creamy.